In the bearing construction for a drive shaft, the bearing construction often employs an inner ring rotation system in terms of simplification of the layout. However, in a vehicle such as a part-time type 4-wheel drive vehicle, mounting of an autolocking hub is presupposed, and a bearing construction of-an outer ring rotation system is often employed in terms of restriction in construction of the autolocking hub.
In the outer ring rotation type bearing construction, as shown in FIG. 11, there is used an outer joint 102 of a drive shaft extending through a hollow sleeve or spindle 104. In the outer joint 102, one end (which is a wheel side end) is supported by being disposed on an autolock hub 132 (or equivalent article) which is fixed to a hub 134 supported on spindle 104 by an axle bearing 136, and the other end is supported on the spindle 104 through a bearing 106 such as a needle bearing. The aforementioned arrangement is one which is not an autolock hub used in a part-time type 4-wheel drive vehicle, but is employed for a full-time 4-wheel drive vehicle-which has a function to transmit rotation of the drive shaft to the hub.
The aforementioned bearing construction for a drive shaft is disclosed in Japanese Patent Application Laid-Open No. 61-238516. In the apparatus for controlling intermittence between the vehicle and a drive mechanism therefor as disclosed in the 61-238516 publication, there is provided a spindle provided with inner and outer rotation supporting surfaces, the spindle being mounted on a vehicle's frame, and an axle portion is supported on a rotational shaft on the inner supporting surface of the spindle through a bearing member.
In the conventional bearing construction of the drive shaft, as shown in FIG. 12, a sleeve bushing 232 with a sliding member 210 is press-fitted into a spindle 204, and an outer joint hub 202 of the drive shaft is inserted into the inner surface of the sliding member 210 of the bushing 232, whereby the outer joint 202 is rotatably slidably movably supported. Note that the sliding member 210 is formed of low friction resin impregnated metal. In this arrangement, the construction is simple, but noises are possibly generated depending upon the use conditions, posing an inconvenience and being disadvantageous in practical use.
Further, as shown in FIG. 13, a bearing 306 for diametrally (perpendicularly) supporting an outer joint hub 302 of the drive shaft is provided between spindle 304 and the outer joint hub 302, and a thrust washer 342 for axially supporting the outer joint hub 302 is provided between the hub 302 and the spindle 304. In this case, the bearing 306 is used for the diametral support which imposes a relatively large load. An inconvenience of generating noises as described above can be avoided, and the thrust washer 342 whose both sides are sliding surfaces is provided for the axial support, which is advantageous in that the sliding member need not be used. However, there is a possibility that in the assembling work, the thrust washer falls, and the assembling is finished in the state that the thrust washer is not mounted, posing an inconvenience that the accuracy and reliance of the assembling work are low.